A high pressure discharge lamp is known from U.S. Pat. No. 5,742,123 and U.S. Pat. No. 6,020,685 and U.S. Pat. No. 6,863,586 in which a ceramic discharge vessel uses a radially layered cermet part at its ends for sealing.
Previously a radial gradient structure has been used in which the gradient changes monotonously from the first innermost layer to the last outermost layer. A gradual graduation of the coefficient of thermal expansion is achieved in the cermet part thereby, so the jump in the coefficients of thermal expansion between the two materials ceramic of the discharge vessel and metal of the feed-through is attenuated as well as possible. Such gradually graduated layers can have different thicknesses. They can be produced using different methods, in particular by immersing, spraying and molding. The individual layers can be circular-cylindrical or the cermet part can also be continuously produced by helical winding.